1. Field of the Invention
The present invention relates to a radio selective calling receiver and a radio selective calling receiving method and in particular to a radio selective calling reception for receiving a message as a result of conference calls.
2. Description of the Prior Arts
As a conventional technique related to conference calls (group calls), a selective call reception system is disclosed in Japanese Unexamined Patent Publication No. Sho 60-9235 whereby identification bits are stored in a memory (ID-ROM) prepared for storing individual numbers so that a single ID-ROM can be employed for handling either individual calls or conference calls.
In addition, disclosed in Japanese Unexamined Patent Publication No. Hei 7-327247 is a radio call reception system that, although not intended for conference calls, is optimal for use in a case where a plurality of persons having different identification codes use a single receiver in common.
Conventionally, at the time a group call is initiated to establish a simultaneous connection with a plurality of radio selective calling receivers, all of the receivers that belong to that group transmit reception messages. As a result, transmission of a message to only one receiver of a specific set (sub-group) in a group is disabled. When a message that can be employed by only one part of a group is transmitted as a group call, an important message that is intended for some receiver and that is stored in a message storage memory would be abandoned upon receipt of a number of unnecessary messages.
To resolve this problem for a conventional radio selective calling receiver, individual numbers for sub-groups must be prepared in addition to individual numbers for groups, or a separate call must be performed for each receiver that belongs to a sub-group. However, according to the former method additional individual numbers must be created, and according to the latter method, each receiver must have an individual number for separate calls in addition to one for conference calls. Furthermore, a large load is placed on a transmitter and there is deterioration of transmission efficiency.